The present invention relates to a lubricating oil supply system for industrial engines, which is capable of automatically supplying lubricating oil when the amount of lubricating oil becomes less than a predetermined level.
Generally, in an industrial engine, it is necessary to supply lubricating oil to a crankcase when the amount of the lubricating oil in the crankcase decreases below the predetermined level due to the consumption of lubricating oil with the operation of the engine. Accordingly, a system which can automatically supply lubricating oil has been employed for this purpose. For example, the assignee proposed in Japanese Utility Model Laid Open No. 55-130008 a lubricating oil supply system for an industrial engine in which pulsation of air pressure in the crankcase is used to vibrate a diaphragm for a pump when the amount of lubricating oil is less than a predetermined level and a necessary amount of lubricating oil is automatically supplied. However, in such a system, the amount of lubricating oil supplied to the crankcase fluctuates due to temperature variation of the oil which is caused by temperature fluctuations of the ambient air and the engine. Namely, at a low temperature, a long time is required to supply a necessary amount of lubricating oil due to an increase of the viscosity of the oil, while at high temperature an excessive amount of the oil is fed due to reduction of the viscosity. Further, such a system of the prior art does not provide any warning or alarm and does not stop the operation of the engine when the temperature of the oil or the diaphragm pump excessively lowers or rises.